HD 17156 is a Sun-like F-type star (about 1.28 solar masses, 6,046 K, 1.52 solar radii), 78.1 light-years from Earth. HD 17156 b was an early eccentric transiting giant, spending most of its orbit far from the star before a brief hot perihelion. HD 17156 b is a 3.26-Jupiter-mass companion, with an orbital period of 21.2 days, at 0.163 AU from its star, and an equilibrium temperature near 888 K, on an eccentric orbit (e ≈ 0.68), discovered in 2007 via radial velocity. The planet betrayed itself through the star's reflex motion — a technique that first revealed worlds around Sun-like stars in the 1990s and remains a workhorse of exoplanet discovery.